Bring in new IDL files and generated code. Update the script that syncs the idl files to deal with …

dart/sdk/lib/web_audio/dartium/web_audio_dartium.dart

 library dart.dom.web_audio;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:html_common';
 import 'dart:nativewrappers';
 import 'dart:typeddata' as _typeddata;
 // DO NOT EDIT
 // Auto-generated dart:audio library.
@@ skipping 403 matching lines @@
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 
 @DocsEditable
 @DomName('AudioDestinationNode')
 class AudioDestinationNode extends AudioNode {
   AudioDestinationNode.internal() : super.internal();
 
-  @DomName('AudioDestinationNode.numberOfChannels')
+  @DomName('AudioDestinationNode.maxChannelCount')
   @DocsEditable
-  int get numberOfChannels native "AudioDestinationNode_numberOfChannels_Getter";
+  int get maxChannelCount native "AudioDestinationNode_maxChannelCount_Getter";
 
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 
 @DocsEditable
@@ skipping 725 matching lines @@
 
 // WARNING: Do not edit - generated code.
 
 
 @DocsEditable
 @DomName('WaveTable')
 class WaveTable extends NativeFieldWrapperClass1 {
   WaveTable.internal();
 
 }